[2] Voltage sags are defined by their magnitude or depth, and duration.
Usually further described using a modifier indicating the magnitude of a voltage variation (e.g. sag, swell, or interruption) and possibly a modifier indicating the duration of the variation (e.g., instantaneous, momentary, or temporary).
"[3] The main goal of the power system is to provide reliable and high-quality electricity for its customers.
Therefore, Monitoring the power system to ensure its performance is one of the highest priorities.
[8] The term sag should not be confused with a brownout, which is the reduction of voltage for minutes or hours.